Nasal interface prong device

ABSTRACT

An infant nasal interface prong device for use with an nCPAP system. The device includes first and second nasal prongs and a base. Each prong includes a bellows segment, a tip, and a lumen. The tip extends from the bellows segment to a tip end and is adapted for insertion with an infant&#39;s naris. The lumen extends through the tip and the bellows segment. In an undeflected state, a central axis of the lumen along the bellows segment is transversely offset from the lumen axis at the tip end. The base is connected to each of the nasal prongs and is adapted for coupling to a CPAP generator. The bellows segment renders the corresponding prong highly flexible relative to the base. The offset positioning of the tip end promotes desired positioning of the base/CPAP generator, relative to the patient and more closely conforms to the expected nasal anatomy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/292,808, filed Dec. 2, 2005, now U.S. Pat. No. 7,640,934, andentitled “Infant Nasal Interface Prong Device”; the entire teachings ofwhich are incorporated herein by reference.

BACKGROUND

The present invention relates to patient nasal interface devices for usewith continuous positive airway pressure (CPAP) systems. Moreparticularly, it relates to a nasal interface prong device fordelivering CPAP therapy to the nasal airways of a patient, such as aninfant.

CPAP therapy has been employed for many years to treat patientsexperiencing respiratory difficulties and/or insufficiencies. Morerecently, CPAP therapy has been advanced as being useful in assistingpatients with under-developed lungs (in particular, infants andespecially premature infants or neonates) by preventing lung collapseduring exhalation and assisting lung expansion during inhalation.

In general terms, CPAP therapy entails the continuous transmission ofpositive pressure into the lungs of a spontaneously breathing patientthroughout the respiratory cycle. A CPAP system generally includes aCPAP generator adapted to create or generate a continuous positiveairway pressure within one or two tubes, along with a patient interfacedevice connected to the generator that serves as a conduit for transferof inhaled and exhaled gases. The CPAP generator can assume a variety offorms, including a fixed flow, ventilator-type system, or a variableflow system.

Similarly, CPAP can be delivered to the patient using a variety ofpatient interface devices, for example an endotracheal tube. Withinfants, however, it is desirable to employ a less invasive patientinterface device, in particular one that interfaces directly orindirectly with the nasal airways via the patient's nares. Such systemsare commonly referred to nasal continuous positive airway pressure(“nCPAP”) systems.

With nCPAP systems, the patient nasal interface device is typicallyeither a mask or a dual prong body. The nasal mask is characterized asdefining a single cavity that is placed over the patient's nose. Thecavity is fluidly connected to the CPAP generator and thus provides aconduit between the CPAP generator and the patient's nasal airways.While non-invasive, it is sometimes difficult to consistently achieveand maintain a fluid-tight seal between the mask cavity and the nasalairways. This is especially true with infants whom otherwise havesmaller facial features and thus facial surface area against which themask can be applied. Conversely, the dual prong device includes twoprongs or cannulas each fluidly connected to the CPAP generator andsized for insertion within a respective naris of the patient. With thistechnique, a relatively stable fluid seal can readily be accomplishedbetween the prongs and the nasal airways. Unfortunately, however, theinventors have discovered several possible shortcomings with currentlyavailable infant CPAP nasal interface prong devices.

For example, nasal interface prong devices are designed to satisfy anoverriding goal of achieving and maintaining a fluid seal within thepatient's nares. The conventional approach for ensuring a fluid seal isto form the prongs to be somewhat soft, along with having an enlargeddiameter along a portion of a length thereof (e.g., a flared tip end orenlarged tip base). This enlarged diameter essentially presses into orlodges against the patient's naris tissue/membrane upon insertion. Tothis end, though soft, conventional prong configurations have little orno mobility (e.g., cannot axially compress or move laterally), leadingto distinct pressure points along the tip end/naris interface. For manypatients, especially infants, this interaction can be quite painful,causing the patient to resist insertion of the nasal prongs and/orlong-term usage. In fact, the delicate tissue associated with thepatient's nares (and especially a premature infant's nares) can bedamaged by long-term contact with the nasal prongs, resulting inpressure sores and even necrosis. Unfortunately, simply softening theprong material is not a viable solution, as it may lead to kinking ofthe prong(s) during use.

Along these same lines, the immobile nature of the conventional nasalinterface prong device cannot accommodate any misalignment of the CPAPgenerator relative to the patient's nose. When the CPAP generator islater moved relative to the patient to correct this misalignment, thenasal interface prong device will also move in a similar fashion, againpotentially leading to painful pressure points within the patient'snares. While efforts have been made to incorporate a flexible segmentinto the nasal prong design, (e.g., Landis, U.S. Publication No.2004/0065330), other concerns arise, such as kinking of the flexiblesection or insufficient lateral resistance to prong collapse duringinsertion within the naris. Further, with other attempts (e.g., Trimbleet al., U.S. Pat. No. 4,782,932), human nasal anatomy has not been fullyaddressed, nor have the anatomical peculiarities commonly encounteredwith infants been accounted for. For example, the nasal septum isunder-developed in many infants, and in particular premature infants.This, in turn, dramatically affects the uniformity of a particular narisdiameter. Because available flexible nasal prong designs cannotself-correct for the naris diameter actually encountered, it isnecessary to have a relatively large number of differently-sized nasalprong devices on hand. As might be expected, healthcare facilities wouldgreatly prefer to not maintain a large inventory of differently-sizedproducts; similarly, physicians may find it difficult and time consumingto select the optimal nasal prong device from a large number ofavailable sizes through trial-and-error.

In light of the above, a need exists for an improved nasal interfaceprong device for use with an nCPAP system, especially for infant patientapplications.

SUMMARY

Some aspects in accordance with principles of the present inventionrelate to an infant nasal interface prong device for use with a nasalcontinuous positive airway pressure (nCPAP) system. The device includesfirst and second nasal prongs and a base. Each prong includes a bellowssegment, a tip, and a lumen. The tip extends from the bellows segmentand is adapted for insertion with an infant's naris. Further, the tipterminates in a tip end opposite the bellows segment. The lumen extendsthrough the tip and the bellows segment. In an undeflected state, acentral axis of the lumen as defined by the bellows segment istransversely offset from a central axis of the lumen as defined at thetip end. The base is connected to each of the nasal prongs and isadapted for coupling to a CPAP generator. In addition, the base definesfirst and second passages fluidly connected to respective ones of thelumens. With this configuration, the bellows segment renders thecorresponding prong highly flexible such that the respective tipsradially pivot relative to the base. Further, the offset positioning ofthe tip end relative to the bellows segment promotes desired positioningof the base, and thus of a CPAP generator assembled thereto, relative tothe patient while at the same time more closely conforming to theexpected nasal anatomy. In one embodiment, the tip is curved inlongitudinal extension from the bellows segment. In another embodiment,the bellows segment is characterized by a reduced wall thickness ascompared to a wall thickness of the tip, and is configured to impart aninward bias onto the tip.

Other aspects in accordance with principles of the present inventionrelate to an infant nasal continuous positive airway pressure (nCPAP)device for use in an nCPAP system. The device includes an nCPAPgenerator and an infant nasal interface prong device. The nCPAPgenerator includes first and second tubes, and is adapted to generate acontinuous positive airway pressure within each of the tubes. The infantnasal interface device is mounted to the tubes and includes first andsecond prongs, and a base. Each of the prongs includes a bellowssegment, a tip, and a lumen. The tip extends from the bellows segmentand is adapted for insertion within an infant's naris. Further, the tipterminates in a tip end opposite the bellows segment. The lumen extendsthrough the tip and the bellows segment such that in an undeflectedstate, a central lumen axis along the bellows segment is transverselyoffset from the central lumen axis at the tip end. The base, in turn, isconnected to each of the nasal prongs and is coupled to the CPAPgenerator. In this regard, the base defines first and second passageseach fluidly connected to a respective one of the lumens. Further, thepassages are fluidly connected to respective ones of the tubes uponfinal assembly. In one embodiment, the base of the interface device anda housing of the CPAP generator define corresponding, non-symmetricalshapes.

Yet other aspects in accordance with principles of the present inventionrelate to an infant nasal interface prong device for use with an nCPAPsystem. The device includes first and second prongs and a base. Eachprong includes a bellows segment, a tip, and a lumen. The tip is adaptedfor insertion within an infant's naris and has a tip body extending fromthe bellows segment and terminating at a tip end. Further, the tip bodydefines a top side forming a convex curve in longitudinal extension anda bottom side forming a concave curve in longitudinal extension. Thelumen extends through the prong and is open at the tip end. With this inmind, in an undeflected state of the prong, a central axis of the lumenas defined by the bellows segment is transversely offset from thecentral axis of the lumen as defined at the tip end. The base isconnected to each of the nasal prongs and is adapted for coupling to aCPAP generator. In addition, the base defines first and second passagesfluidly connected to respective ones of the lumens. In this regard, theprongs extend in a juxtaposed fashion relative to the base. The bellowssegment of each prong is configured to be non-symmetrical relative to anaxis of the corresponding tip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of an infant nasal interface prongdevice in accordance with principles of the present invention;

FIG. 2A is a bottom plan view of the interface device of FIG. 1;

FIG. 2B is a bottom, longitudinal cross-sectional view of the interfacedevice of FIG. 1;

FIG. 2C is a bottomplan view of an alternative embodiment infant nasalinterface prong device;

FIG. 3A is a side plan view of the interface device of FIG. 1;

FIG. 3B is a side, longitudinal cross-sectional view of the interfacedevice of FIG. 1;

FIG. 4 is a rear view of the interface device of FIG. 1;

FIG. 5A is an exploded, perspective view of an nCPAP device inaccordance with principles of the present invention including theinterface device of FIG. 1 and an nCPAP generator; and

FIG. 5B is a cross-sectional view of the nCPAP device of FIG. 5A uponfinal assembly.

DETAILED DESCRIPTION

One embodiment of an infant nasal interface prong device 20 for use witha nasal continuous positive airway pressure (nCPAP) system is shown inFIG. 1. The interface device 20 includes a first prong 22, a secondprong 24, and a base 26. Details on the various components are providedbelow. In general terms, however, the prongs 22, 24 extend in agenerally juxtaposed fashion from the base 26, and each define a lumen28, 30 (referenced generally), respectively. The base 26 is configuredto establish a fluid connection between an nCPAP generator (shown at 150in FIG. 5A) and the lumens 28, 30. To this end, the first and secondprongs 22, 24 are each configured for insertion within a patient'snaris. Further, the prongs 22, 24 are adapted to be highly flexible,allowing for longitudinal movement and lateral/transverse pivotingrelative to the base 26 without collapsing of the corresponding lumen28, 30. As such, the patient interface device 20 readily accommodatesany slight misalignments upon securement to the patient, whereby a tipportion of each of the prongs 22, 24 effectively “floats” relative tothe base 26. As described below, in some embodiments, the interfacedevice 20 incorporates additional features that further reduce possiblepatient discomfort.

As used throughout the specification, relative directional terminology,such as “proximal” and “distal” are used with reference to a position ofthe interface device 20 relative to a patient to whom the interfacedevice 20 is applied. Thus, “proximal” is closer to the patient ascompared “distal”. Further, spatial terminology, such as “horizontal,”“vertical,” “top,” “bottom,” etc., are with reference to an uprightorientation of the device 20 as shown in FIG. 1, but are in no waylimiting.

The interface device 20 is preferably an integral, homogenous structure,formed of a surgically safe, compliant material capable of achieving afluid seal when applied to a patient's skin and nares. For example, andin one embodiment, the interface device 20 is a molded silicone part.Alternatively, other materials such as soft vinyls, thermoplasticelastomers, etc., are also acceptable. However, reference to certaindimensional attributes in the following discussion relates to oneembodiment in which the interface device 20, and in particular each ofthe prongs 22, 24, is a homogenous, thin-walled structure formed ofsilicone or silicone-like material.

With the above general parameters in mind and with specific reference toFIGS. 2A and 2B, in one embodiment each of the prongs 22, 24 is definedby or includes a tip 40, a bellows segment 42, and a foot 44. The prongs22, 24 extend in a generally juxtaposed fashion from the base 26, andare identical. Thus, the following description of the first prong 22applies equally to the second prong 24.

The lumen 28 extends through the tip 40, the bellows segment 42, and thefoot 44, such that the prong 22 is a generally tubular body defining alumen central axis A (referenced generally in FIG. 2B). A spatialorientation of the lumen central axis A varies between the tip 40, thebellows segment 42, and the foot 44, with these variations beingreflected in the figures as A_(tip), A_(bellows), and A_(foot). Asdescribed below, the variation in spatial orientation of the centrallumen axis A occurs both horizontally (reflected in FIG. 2B) andvertically (reflected in FIG. 3B) relative to an upright position of theinterface device 20.

The tip 40 extends proximally from the bellows segment 42, andterminates at a tip end 46 opposite the bellows segment 42. As furthershown in the view of FIGS. 3A and 3B, the tip end 46 is flared relativeto a remainder of the tip 40. That is to say, in one embodiment the tipend 46 defines a proximally increasing outer diameter for more readilyengaging or contacting a surface of the patient's naris upon insertionof the tip 40 within the naris. Further, and in one embodiment, across-sectional wall thickness of the tip end 46 is decreased ascompared to a wall thickness of the remainder of the tip body 40 as bestshown in FIG. 3B. That is to say, the tip 40 can be described asincluding the tip end 46 and a tip body 48, with the prong 22 beingformed by a continuous side wall 50. With these definitions in mind, theside wall 50 tapers in thickness (proximally) along the tip end 46 to athickness that is at least 25% less than a maximum nominal thickness ofthe side wall 50 along the tip body 48. This reduced wall thicknessrenders the tip end 46 highly compliant and thus less likely to createpressure points when pressed against an interior of the patient's naris.

A spatial orientation of the tip body 48 is dictated by an arrangementof the corresponding bellows segment 42/foot 44 as described below, withthe prongs 22, 24 being arranged to each generally define an interiorside 52 a, 52 b, respectively, and an exterior side 54 a, 54 b,respectively, as shown in FIG. 2A. The interior side 52 a of the firstprong 22 “faces” the interior side 52 b of the second prong 24 (andvice-versa); the exterior side 54 a or 54 b is defined opposite thecorresponding interior side 52 a or 52 b. With this in mind, the tipbodies 48 are, in one embodiment, configured in combination with spatialorientation dictated by the bellows segment 42/foot 44 such that theinterior sides 52 a, 52 b along the tip bodies 48 are substantiallyparallel (e.g., with 5 degrees of a true parallel relationship), whereasthe exterior sides 54 a, 54 b along the tip bodies 48 taper slightlytoward one another in proximal extension. For example, a lateraldistance between the interior sides 52 a, 52 b at the corresponding tipbody 48/bellows segment 42 intersection is substantially the same as alateral distance at the tip body 48/tip end 46 intersection; conversely,a lateral distance between the exterior sides 54 a, 54 b decreases fromthe corresponding tip body 48/bellows segment 42 intersection to the tipbody 48/tip end 46 intersection. This one configuration of the tipbodies 48 establishes a first septal relief zone 56 (referencedgenerally in FIG. 2A) that limits possible formation of pressure pointsalong the patient's septum (that is otherwise between the interior sides52 a, 52 b of the tip bodies 48 upon insertion of the prongs 22, 24) dueto the substantially parallel relationship. Instead, primary contact(preferably all contact) between the prongs 22, 24 and the patient'sseptum occurs only at the tip ends 46. For neonates havingunderdeveloped septums, this absence of pressure points essentiallyeliminates a recognized cause of septal necrosis found with use ofconventional nasal prong devices. Conversely, the tapered relationship(relative to a true parallel relationship) established by the exteriorsides 54 a, 54 b conforms to the expected naris anatomy (e.g., nasalorifice and nasal entrance). Alternatively, the tip bodies 48 can assumeother shapes relative to the interior and/or exterior sides 52 a, 52 b,54 a, 54 b.

An additional feature of the tip 40 in accordance with one embodiment isbest reflected in the views of FIGS. 3A and 3B. To this end, FIGS. 3Aand 3B depict the interface device 20 in an “upright” orientationwhereby the prong 22 can be described as having or defining a top side60 (referenced generally) and a bottom side 62 (referenced generally).Relative to the patient's anatomy, upon insertion into the naris, thetop side 60 will reside closer to the patient's nasal bridge as comparedto the bottom side 62; conversely, the bottom side 62 will reside moreclosely to the patient's upper lip as compared to the top side 60. Withthese conventions in mind, the tip body 48 defines a longitudinalcurvature that approximates the expected naris anatomy, and furtherpositions the base 26, and thus the nCPAP generator (not shown)otherwise attached to the base 26, at a desired position relative to thepatient (i.e., off of the patient's face). For example, in oneembodiment, a proximal region 66 of the tip body 48 has, in longitudinal(proximal) extension relative to the bellows segment 42, a convexcurvature along the top side 60 and a concave curvature along the bottomside 62. In one embodiment, a radius of curvature associated with theproximal region top side 60 differs from that associated with theproximal region bottom side 62, with the proximal region top side 60having a larger radius of curvature. Alternatively, the radius ofcurvature of the proximal region 66 can be uniform. Even further, inother embodiments, the tip body 48 exterior is linear in longitudinalextension. Along these same lines, in one embodiment, the central axis Aof the lumen 28 as defined by the tip body 48 (i.e., A_(tip)) is arcuateor curved relative to a side plane (or vertical, longitudinalcross-section as shown in FIG. 3B) of the device 20; alternatively, thecentral axis A_(tip) can be linear.

Regardless, longitudinal extension of the tip body 48 from the bellowssegment 42 includes a transverse or radial component, such that the tipend 46 is transversely offset (e.g., vertically above) relative to thebellows segment 42 in the upright orientation of the interface device 20as shown in FIGS. 3A and 3B. In one embodiment, this vertical offset ischaracterized by the central axis A of the lumen 28 along the bellowssegment 42 (i.e., A_(bellows)) being transversely or vertically offsetrelative to the central axis A of the lumen 28 at the tip end 46 (inlongitudinal, side planar view of the device 20). The vertical offsetcan alternatively be characterized relative to the tip body 48. Moreparticularly, the tip end 46 defines a lumen center point C_(end).Similarly, the tip body 48 defines a lumen center point C_(body) at theintersection with the bellows segment 42 (i.e., a trailing end of thetip body 48). Relative to the upright orientation of FIG. 3B, the tipend center point C_(end) is transversely above the tip body center pointC_(body). As a point of reference, as described below the bellowssegment 42 is flexible, such that the tip 40 can pivot or deflectrelative to the foot 44 with the bellows segment 42 internally flexingor deflecting. Thus, spatial relationships or attributes describedherein are relative to the prong 22 in an undeflected or natural state.

The bellows segment 42 extends distally from the tip 40, and isconfigured to permit and facilitate pivoting and/or flexing of the tip40 relative to the foot 44 (and relative to the base 26). Theflexibility afforded by the bellows segment 42 can be accomplished witha variety of designs. For example, the bellows segment 42 is configuredsuch that the tip 40 can pivot in a multitude of directions relative tothe foot 44 and/or base 26 (e.g., vertically up or down, horizontallyside-to-side, etc.), move distally toward the foot 44/base 26 (viacollapsing of the bellows segment 42), etc. In one embodiment, however,the bellows segment 42 is configured to allow pivoting or swiveling ofthe tip 40 with minimal force and without kinking (i.e., the bellowssegment 42 does not overtly collapse or fold over in a manner that wouldotherwise result in a substantial increase in flow resistance). Tobetter understand this feature, a brief explanation of certain spatialfeatures associated with the foot 44 and the base 26 is helpful.

As previously described, the base 26 facilitates assembly of the patientinterface device 20 to an nCPAP generator (shown at 150 in FIG. 5A), anddefines a distal or rear face 70. The rear face 70 abuts against acorresponding surface of the nCPAP generator, and thus defines a planerelative to which portions of the patient interface device 20 can becompared or described. In addition, the base 26 forms first and secondpassages 72, 74 that are fluidly connected to respective ones of thelumens 28, 30 as shown in FIG. 2B. In this regard, fluid connectionbetween the lumens 28, 30 and the passages 72, 74, respectively, isachieved at an interface or transition of the respective foot 44 and thebase 26.

With the above conventions in mind, and with specific reference to thelongitudinal cross-sectional bottom view of FIG. 2B, in one embodiment,the bellows segment 42 is formed via the side wall 50 defining first,second, and third sections 90-94. The first section 90 extendsproximally from the foot 44 to define a first bend angle W. The secondsection 92 extends proximally from the first section 90 to define asecond bend angle X. The third section 94 extends proximally from thesecond section 92 to define a third bend angle Y. Finally, the thirdsection 94 and the tip body 48 combine to define a fourth bend angle Z.In general terms and in one embodiment, the sections 90-94 combine todefine a single outboard wall segment (at the intersection of the secondand third sections 92, 94) and do not include or define an annulartrough.

A transverse plane defined at an intersection of the first section 90and the foot 44 is non-parallel relative to the plane of the rear face70 as shown in FIG. 2B. That is to say, the interior side 80 at thefirst section 90/foot 44 intersection is longitudinally closer to therear face 70 as compared to the exterior side 54 a at the first section90/foot 44 intersection. This characteristic is alternatively describedby the interior side 52 a of the foot 44 having a longitudinal lengthless than that of the exterior side 54 a of the foot 44. Regardless,proximal extension of the first section 90 relative to the foot 44imparts an inward “tilt” onto the bellows segment 42. Further, the firstbend angle W varies about a circumference or perimeter of the firstsection 90. More particularly, the first bend angle W is greater at theexterior side 54 a as compared to the interior side 52 a, and is greaterthan 180° at least along the exterior side 54 a such that as a whole,the first section 90 projects radially inwardly (relative to the centralaxis A of the lumen 28) in longitudinal (proximal) extension from thefoot 44.

A spatial orientation of the second section 92 relative to the firstsection 90 continues the above-described inward “tilt”, with theexterior side 82 at the second section 92/first section 90 intersectionbeing longitudinally further from the rear face 70 as compared to theinterior side 80 at the second section 92/first section 90 intersection.In one embodiment, the second bend angle X is substantially uniformabout a circumference or perimeter of the first section 90/secondsection 92 intersection, but in alternative embodiments can vary.Regardless, the second bend angle X is less than 180°, preferably lessthan 120°, and even more preferably less than 90°, such that the secondsection 92 projects radially outwardly in longitudinal (proximal)extension from the first section 90. This, in turn, results in the lumen28 having an increasing diameter relative to a longitudinal (proximal)extension of the second section 92 from the first section 90.

A spatial orientation and configuration of the third section 94 relativeto the second section 92 compensates for the planar offset describedabove. In particular, the third bend angle Y, as defined by the proximalextension of the third section 94 from the second section 92, variesalong a circumference or perimeter of the second section 92/thirdsection 94 intersection, with the third bend angle Y being greater alongthe exterior side 82 as compared to the interior side 80. For example,in one embodiment, the third bend angle Y along the exterior side 54 aapproaches 270°, whereas the third bend angle Y along the interior side52 a is approximately 210°. Alternatively, other dimensionalrelationships are equally acceptable; preferably, however, an entiretyof the third bend angle Y is greater than 180° such that the thirdsection 94 projects radially inward with longitudinal (proximal)extension from the second section 92. In other words, the third section94 defines the lumen 28 to have a proximally decreasing diameter. As aresult of this spatial orientation, a longitudinal distance of the thirdsection 94/tip body 48 interface relative to the rear face 70 issubstantially uniform at the interior and exterior sides 52 a, 54 a.

Finally, the fourth bend angle Z as defined by the third section 94 andthe tip body 48, varies about a circumference of the prong 22. Moreparticularly, in one embodiment, the fourth bend angle Z is preferablygreater along the interior side 52 a as compared to the exterior side 54a. As a result, and relative to the bottom longitudinal view of FIG. 2B,the tip body 48 extends in a generally perpendicular fashion relative toa plane of the rear face 70.

The above-described bellows segment sections 90-94 and bend angles X-Z(and primarily, in one embodiment, the second and third section 92, 94and the second bend angle X) combine to allow the bellows segment 42 torepeatedly pivot or swivel in virtually any direction as well ascompress longitudinally, all without kinking. In addition, the bellowssegments 42 collectively maintain the interior side 52 a, 52 b lateralspacing described above with respect to the tip bodies 48 so as to avoidovert contact with the patient's septum. With respect to the spatialorientation attribute, the first passage 72 formed by the base 26defines a passage axis P. Relative to the passage axis P, the centralaxis of the foot 44 (A_(foot)) projects laterally outwardly withproximal extension of the foot 44 from the base 26. Conversely, thecentral axis of the bellows segment 42 (A_(bellows)) projects laterallyinwardly with proximal extension of the bellows segment 42 from the foot44. Finally, the central axis of the tip 44 (A_(tip)) projects primarilylongitudinally (relative to a horizontal plane) with proximal extensionof the tip 40 from the bellows segment 42. Thus, the tip 40 is laterallyoffset relative to bellows segment 42, with a majority of the bellowssegment 42 surface area residing at the exterior side 54 a (compared tothe interior side 52 a). Thus, the bellows segment 42 can be describedas being non-symmetrical in one or more respects. For example, thebellows segment 42 is non-symmetrical relative to the central tip axisA_(tip). Further, an exterior shape of the bellows segment 42 isnon-symmetrical relative to the central bellows segment axisA_(bellows).

Inward deflection or pivoting of the tip 44 is facilitated primarily bythe second section 92 compressing toward the first section 90 along theinterior side 52 a, and expanding away from the first section 90 alongthe exterior side 54 a (via the second bend angle X); a converserelationship occurs with outward deflection. The enhanced thickness andangular relationship of the second and third sections 92, 94 along theexterior side 54 a ensures that this pivoting movement occurs withoutkinking and provides continuous support to the desired longitudinalextension of the tip 40. That is to say, by forming the bellows segment42 to include laterally outwardly extending sections (as compared to areduced thickness, longitudinal or annular trough), the bellows segment42 provides a degree of lateral resistance to compression so that thetip 40 can be inserted through a nasal opening without collapsing.Conversely, while the bellows segment 42 along the interior side 52 aalso permits low force-induced pivoting, a structural mass is of areduced size so as to maximize the lateral distance between the interiorsides 52 a, 52 b. Thus, a second septal relief zone 100 (referencedgenerally in FIG. 2A) is established between the bellows segments 42 asa continuation of the first septal relief zone 56 (established betweenthe tip bodies 48).

The above-described configuration of the bellows segment 42 results inthe prong 22 being able to accommodate for unexpected anatomicalconfigurations of, or deviations in, the patient's septum during use.When the tip 40 inserted within the patient's naris, the bellows segment42 essentially causes the tip 40, and in particular the tip end 46, tosearch for the septum or interior region of the naris via the inwardangular orientation, and maintains a seal against the septum. Inalternative embodiments, however, the bellows segment 42 can assume avariety of other configurations. For example, the bellows segment 42 canhave or define more or less than three of the sections 90-94, and thebend angles W-Z can differ from that previously described. Further, thesections 90-94 and/or the bend angles W-Z can be selected to create adirectional bias within the bellows segment 42 whereby the bellowssegment 42 more readily deflects in one direction as compared toanother. In other embodiments, and as shown for example by thealternative embodiment infant nasal interface prong device 20′ of FIG.2C, one or more ribs 102 can be formed adjacent or along the bellowssegment 42. The ribs 102 provide a tactile indication when the bellowssegment 42 is overtly compressed or collapsed, otherwise implicatingnaris insertion complications (e.g., the ribs 102 resist furthercontraction when contacted, and can “force” the bellow segment 42 torevert back toward an uncompressed state). The ribs 102 can assume avariety of forms, and can be provided at various locations along one orboth of the foot 44 and/or the bellows segment 42.

Returning to the device 20 of FIG. 1, to further enhance a flexibilityof the bellows segment 42, in one embodiment at least a portion of thebellows segment 42 is characterized by a reduced thickness of the sidewall 50 as compared to a thickness of the side wall 50 along the tipbody 48 and the base 26. For example, and as shown in FIG. 3B, in oneembodiment an entirety of the bellows segment 42, including the first,second, and third sections 90-94, are each characterized by a wallthickness that is much less than that of the base 26. Further, at leastportions of the first, second, and third sections 90-94 have a wallthickness less than that of the tip body 48. For example, in oneembodiment, at least a portion of the bellows segment 42 (e.g., thefirst and second segment 90, 92 in regions of one or both of theinterior and exterior sides 52 a, 54 a) has a wall thickness that is atleast 25% less than a maximum nominal wall thickness of the tip body 48.Regardless, by forming at least a portion of the bellows segment 42 tohave a reduced wall thickness as compared to the base 26 and the tipbody 48, an overall flexibility of the bellows segment 42 is enhanced,yet the base 26 and the tip body 48 are provided with sufficientstructural strength and rigidity to maintain the prong 22 (or 24) in adesired shape and orientation during naris insertion and delivery ofCPAP therapy.

As previously described, the foot 44 extends from the base 26 andpositions the bellows segment 42 (and thus the tip body 48) at a desiredangular orientation relative to the rear face 70 of the base 26. Inaddition, and in one embodiment, the foot 44 of the first prong 22combines with the foot 44 of the second prong 24 to continue the secondseptal relief zone (designated at 100 in FIG. 2A) described above. Moreparticularly, relative to the bottom planar view, the interior side 52 aat the foot 44 includes a radial outward component in proximal extensionfrom the base 26. This, in turn, establishes a transverse spacingbetween the respective feet 44, resulting in a third septal relief zone104 (referenced generally in FIG. 2A). The third septal relief zone 104minimizes overt contact with the patient's nasal septal area (as well asthe exterior skin thereof) upon insertion of the prongs 22, 24 withinthe patient's nares, thus minimizing skin breakdown in this delicatearea and increasing patient comfort. In one embodiment, the septalrelief zones 56, 100, 104 are collectively configured such that aminimum lateral distance between the prongs 22, 24 is established at thetip ends 46. Alternatively, the foot 44 can assume a variety of otherconfigurations, in fact, in some alternative embodiments, the foot 44 iseliminated.

With reference to FIGS. 2B and 4, the base 26 extends from the feet 44and, as previously described, forms the first and second passages 72,74, as well as a channel 110. Once again, the passages 72, 74 extend ina longitudinal fashion through a thickness of the base 26, and arefluidly connected to respective ones of the lumens 28, 30. As describedin greater detail below, the passages 72, 74 are sized for assembly overcorresponding components of a CPAP generator device (shown at 150 inFIG. 5C), and thus are open relative to the rear face 70 of the base 26.Thus, the passages 72, 74 provide mechanisms for fluidly connecting theCPAP generator device to the lumens 28, 30. The channel 110 extendsbetween, and is fluidly connected to, the passages 72, 74. In addition,while the channel 110 is open at the rear face 70, the channel 110 isnot directly fluidly connected to the lumens 28, 30. As described ingreater detail below, the channel 110 is sized and shaped in accordancewith certain features of one embodiment CPAP generator, and facilitatessampling or tapping of pressure within the device. Thus, the channel 110can assume a wide variety of forms in terms of size, shape, etc. Infact, in alternative embodiments, the channel 110 is eliminated.

The base 26 is, in one embodiment, sized and shaped for interfacing witha corresponding component of a CPAP generator (shown at 150 in FIG. 5C)and fluidly connecting the passages 72, 74 to the CPAP generator device.In this regard, an exterior of the base 26 defines a perimeter 120 (bestshown in FIG. 4) that includes opposing first and second side edges 122,124, and opposing first and second end edges 126, 128. In oneembodiment, a perimeter shape of an intersection or transition of thefirst side edge 122 to each of the end edges 126, 128 differs from theperimeter shape of the transition or intersection of the second sideedge 124 with the end edges 126, 128. For example, in one embodiment, atransition of the second side edge 124 to each of the end edges 126, 128is characterized as being arcuate or curved in perimeter shape, having arelatively large radius of curvature. In contrast, a transition of thefirst side edge 122 to each of the end edges 126, 128 is characterizedas defining a relatively distinct corner, having a radius of curvaturethat is less than that of the second side edge 124/end edge 126, 128transitions. Thus, a lateral length of the first side edge 122 isgreater than that of the second side edge 124. This one preferredconfiguration of the perimeter 120 corresponds with the feature(s) ofthe CPAP generator device (described below) so as to ensure a desired,proper orientation of the base 26, and thus of the prongs 22, 24,relative to the CPAP generator device upon final assembly.

For example, FIG. 5A illustrates a portion of one embodiment CPAPgenerator device 150 with which the patient interface device 20 isuseful in accordance with principles of the present invention. Detailson the generator device 150 are provided in U.S. application Ser. No.11/293,883 entitled “Nasal Continuous Positive Airway Pressure Deviceand System,” filed on Dec. 2, 2005 and having attorney docket numberRT-6274, the teachings of which are incorporated herein by reference. Ingeneral terms, the CPAP generator device 150 includes first and secondtubes 152, 154 laterally surrounded by a housing 156 and fluidlyconnected to a fluid supply port 158. During use, the CPAP generatordevice 150 receives fluid flow via the support port 158 and generates acontinuous positive airway pressure within each of the tubes 152, 154.With these general concepts in mind, the passages 72, 74 of the base 26are sized for mating over a respective one of the tubes 152, 154, andthe base 26 is sized for being received and frictionally retained withinthe housing 156. In this regard, an interior perimeter shape of thehousing 156 corresponds with the perimeter 120 of the base 26 aspreviously described.

In particular, the differing lengths of the side edges 122, 124, as wellas the curved and corner-shaped transition regions previously describedprevents a user from accidentally attempting to insert the base 26 intothe housing 156 in an orientation opposite to that desired (i.e., theupright orientation). That is to say, the base 26/housing 156 interfacepermits only one orientation of the base 26, and thus of the prongs 22,24, relative to the CPAP generator device 150.

FIG. 5B partially illustrates assembly of the base 26 to the CPAPgenerator device 150, and in particular, the first passage 72 over thefirst tube 152 and the second passage 74 over the second tube 154. Asshown, each of the tubes 152, 154 includes a radial slot 160 that isotherwise fluidly connected to the channel 110 upon final assembly ofthe base 26 within the housing 156. With this one arrangement, then,airflow within the tubes 152, 154 is allowed to flow from the tubes 152,154/base 26 interface via the channel 110, for subsequent pressuremonitoring. In one embodiment, a depth and a width of the channel 110 iscorrelated with a diameter of the passages 72, 74 to minimize formationof back pressure within the device 20 while still affording the abilityto accurately sample pressure being delivered to the patient. To thisend, it has surprisingly been found that by forming the channel 110 tohave a depth that is at least 30% of the diameter of either passage 72,74 (at the rear face 70) and a width that is at least 25% of either thepassage 72, 74 diameters, significant back pressure will not begenerated at expected CPAP levels.

Although the patient interface device 20 has been described inconnection with certain features of the CPAP generator device 150, awide variety of differing CPAP device configurations can also beemployed. That is to say, the patient interface device 20 in accordancewith principles of the present invention is not limited to any oneparticular CPAP device design.

The infant nasal interface prong device in accordance with principles ofthe present invention provides a marked improvement over previous prongdesigns. The thin-walled, bellows segment allows the prong to easilypivot and/or flex relative to the base (and thus the CPAP generator towhich the base is assembled). This attribute allows the patientinterface device to accommodate any misalignments of the CPAP generatorand/or related fixation devices relative to the patient, and furtherminimizes or eliminates pressure point(s) on the infant's/patient'snasal or facial anatomy that might otherwise be created by CPAPgenerator misalignment. To this end, the curved shape of the prongs moreclosely matches an expected anatomy of the patient's naris, and allowsthe CPAP generator device to be located “off” of the patient's face.Finally, the inward bias of the prongs readily accommodates deviationsin the patient's septal anatomy.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the present invention.

1. A nasal interface prong device, the device comprising: first andsecond nasal prongs each including: a bellows segment, a tip having atip body extending from the bellows segment and terminating in a tip endopposite the bellows segment, the tip body including a side forming aconcave curve, a lumen extending through the prong and open at the tipend, wherein in an undeflected state, a central axis of the lumen asdefined by the bellows segment is transversely offset from a centralaxis of the lumen as defined by the tip end.
 2. The nasal interfacedevice of claim 1, wherein relative to an upright orientation of thedevice, each prong is characterized by the central axis of the lumen asdefined by the bellows segment being vertically offset from the centralaxis of the lumen as defined by the tip end in an undeflected state. 3.The nasal interface device of claim 1, wherein a central axis of thefirst passage is transversely offset from the central axis of the firstlumen defined by the corresponding tip end.
 4. The nasal interfacedevice of claim 1, wherein the central axis of each prong is non-linear.5. The nasal interface device of claim 1, wherein relative to anorientation upon insertion within a naris, the tip body defines top sideand a bottom side, and further wherein at least a portion of the topside forms a convex curve and at least a portion of the bottom sideforms the concave curve.
 6. The nasal interface device of claim 1,wherein relative to an upright of the device, each prong ischaracterized by the central axis of the lumen as defined by the bellowssegment being horizontally offset from the central axis of the lumen asdefined by the tip in an undeflected state.
 7. The nasal interfacedevice of claim 1, wherein each of the prongs defines an interior siderelative to the opposing prong, and further wherein in the undeflectedstate, the interior sides are substantially parallel.
 8. The nasalinterface device of claim 1, wherein the bellows segment isnon-symmetrical.
 9. The nasal interface device of claim 1, wherein thebellows segment includes a plurality of sections combining to define aplurality of bends each having a bend angle, and further wherein thebellows segment is configured such that in an undeflected state, atleast one of the bend angles is non-uniform about a circumference of thecorresponding prong.
 10. The nasal interface device of claim 9, whereinthe prongs extend in a juxtaposed fashion such that each prong definesan interior side and exterior side, and further wherein in anundeflected state, at least one of the bend angles differs at theinterior side as compared to the exterior side.
 11. The nasal interfacedevice of claim 1, wherein each bellows segment includes a trailing endopposite the tip end, and further wherein in an undeflected state, atransverse plane defined by the trailing end is not perpendicular to thecentral axis of the lumen at the tip end.
 12. The nasal interface deviceof claim 1, wherein each prong is formed by a continuous wall having anominal thickness along the tip that is greater than a thickness of thewall along at least a portion of the bellows segment.
 13. The nasalinterface device of claim 1, wherein each prong further includes a foot,and further wherein a nominal wall thickness of the foot is greater thana wall thickness along at least a portion of the corresponding bellowssegment.
 14. The nasal interface device of claim 13, wherein the feetare configured to collectively define a septal relief zone.
 15. Thenasal interface device of claim 13, wherein each prong is configuredsuch that in an undeflected state, the central axis of the lumen alongthe foot is not parallel with the central axis of the lumen at the tipend.
 16. The nasal interface device of claim 13, wherein in anundeflected state, the central axis of the lumen along the foot is notparallel with the central axis of each lumen along the tip body.
 17. Thenasal interface device of claim 1, wherein each tip end is flaredrelative to the corresponding tip body such that each tip end defines anincreasing outer diameter with respect to a diameter of thecorresponding tip body.
 18. The nasal interface of claim 1, furthercomprising a base connected to each of the nasal prongs and adapted forcoupling to a continuous positive airway pressure generator, the baseforming first and second passages fluidly connected to respective onesof the first and second lumens.
 19. The nasal interface device of claim18, wherein the base is configured to define, in transversecross-section, opposed first and second side edges and opposed first andsecond end edges, and further wherein a transition between a first endedge and the first side edge defines a curve and a transition betweenthe first end edge and the second side edge is a corner.
 20. The nasalinterface device of claim 18, wherein the base further forms a channelextending between, and fluidly connected to, the first and secondpassages.
 21. A nasal interface device, the device comprising: first andsecond nasal prongs each including: a bellows segment, a tip having atip body extending from a bellows segment and terminating in a tip endopposite the bellows segment, the tip end being flared relative to thetip body so as to define an increasing outer diameter with respect to adiameter of the tip body, and a lumen extending through the prong andopen at the distal end.
 22. The nasal interface device of claim 21,wherein in an undeflected state, a central axis of the lumen as definedby the bellows segment is transversely offset from a central axis of thelumen defined by the tip end, and
 23. The nasal interface device ofclaim 21, further comprising a base connected to each of the nasalprongs and forming first and second passages fluidly connected torespective ones of the first and second lumens, wherein the passages arefluidly connected to respective ones of the first and second tubes uponfinal assembly.
 24. The nasal interface device of claim 21, wherein thetip body defines a top side and a bottom side, and further wherein atleast a portion of the top side forms a convex curve and at least aportion of the bottom side forms a concave curve.
 25. The nasalinterface device of claim 21, wherein the first and second prongs extendin a juxtaposed fashion with the bellows segment of each of the prongsbeing non-symmetrical relative to an axis of the tip body.
 26. The nasalinterface device of claim 21, wherein each of the prongs defines aninterior side relative to the opposing prong, and further wherein, in anundeflected state, the interior sides are substantially parallel. 27.The nasal interface device of claim 21, wherein each bellows segmentincludes a trailing end opposite the tip end, and further wherein in anundeflected state, a transverse plane defined by the trailing end is notperpendicular to a central axis of the lumen at the tip end.